Push Button Station and Relay

Slides:



Advertisements
Similar presentations
Basic Electricity.
Advertisements

Contactors & Relays.
Three-Phase AC machines
HYDRAULICS & PNEUMATICS
©2011, The McGraw-Hill Companies, Inc. Chapter 4.
Contactor, Relays and Overloads
Lesson 15: Dc Motor Control Components and Diagrams
Components, Symbols, and Circuitry of Air-Conditioning Wiring Diagrams
Section 4: Electric Motors
E2 Motors and Motor Starting
Electrical Electricity Fuses Relays Solenoids Electrical Testing
1 HVAC 214 Electricity For Oil Heat Fan Center Relays.
BEX100 – Basic Electricity
Troubleshooting Electric Control Devices
Industrial Machine Control
Ignition System.
Ladder Diagram Symbols Flashcard Exercise Get Started.
Seal-in is not a hotel in Monterey This presentation is partially animated. Only use the control panel at the bottom of screen to review what you have.
Electrical Control Components
E2 Motors and Motor Starting
Electromagnetic relay
Unit 4 Symbols.
E1 – Electrical Fundamentals
Electrical Switches 1 st SEM Information Technology UNIVERSAL COLLEGE OF ENGINEERING & TECHNOLOGY SUBJECT: ELEMENTS OF ELECTRICAL ENGINEERING( )
Ag. Mechanics for Beginning Teachers
Electric Energy Notes.
Basic study of a switch Unit 3.Lesson 3. A switch Purpose A switch is a mechanical device used to connect and disconnect a circuit at will Parts seen.
Symbols and Schematic Diagrams
REDA Production Systems
Design of starters for AC motors C.K. PITHAWALA COLLAGE OF ENGINEERING & TECHNOLOGY Group no - 3 Name Enrolment no Chaudhari Darshan M Chaudhari.
BASIC ELECTRICITY AND MAGNETISM
ACTIVE LEARNING ASSIGNMENT TOPIC NAME :- DC MOTOR STARTERS ELEMENTS OF ELECTRICAL DESIGN ( ) AY Course co-ordinator:- SAMIR B PATEL PREPARED.
Electricity and its characteristics…  Conventional Flow theory states that flow of electrons is from positive to negative.(Accepted in the transportation.
UNIVERSAL COLLEGE OF ENGINEERING 1st SEM Information Technology
THREE PHASE FAULT ANALYSIS WITH AUTO RESET ON TEMPORARY FAULT AND PERMANENT TRIP OTHERWISE Submitted by:
PowerPoint to Accompany Lessons in
A Presentation on DC Generator.
Topics covered in this presentation:
Relay operation Water level Indicator
Presented by SARAVANA KUMAR . M (EEE III Year) SBM CET
PRESENTED BY:AMOD SHAKYA. Power Circuit –connectoin with motor using contactor Control Circuit-using switch make a holding circuit.
GROUND-FAULT GROUND-CHECK MONITOR
Electronic Control Systems Week 4 – Relays and Solenoids
ELECTRICAL INSTALLATION AND MAINTENANCE (EIM) 5 INSTALL ELECTRICAL PROTECTIVE DEVICES FOR DISTRIBUTION, POWER, LIGHTING, AUXILIARY, LIGHTNING PROTECTION.
Korea University of Technology and Education
relays a relay is a switch that is turned on or off using electricity
Workbook Section.
Electric Energy Notes.
Electromagnetic Devices
EET 323 – Electrical System Design Lecture 4: Wiring Devices
Overcurrent Protection— Fuses and Circuit Breakers
EET 323 – Electrical System Design Lecture 9: Grounding
Wiring the Light and Relay
Contactor A contactor is an electrically controlled switch (relay) used for switching an electrical power circuit. A contactor is typically controlled.
Programmable Logic Controllers (PLCs)
Topic 3: Connecting and Starting Three Phase Induction Motors
Introduction to Electro-pneumatic
Level 2 Electrical and Electronic 3
Fluid Power System Electrical Control
Presentation transcript:

Push Button Station and Relay Motor Control Circuit Push Button Station and Relay L 1 C N Stop Start Coil Auxiliary Contact Ladder Diagram for 120 V Motor Control Circuit

Main Points   Why use a motor control circuit? Motor controls allow for the use of lower amperage and/or lower voltage to control large loads. Safer – less arcing between switch contacts, lower amperage and lower voltage; safer for operators and maintenance More efficient - allows for use of smaller conductors in the control circuit wiring, connections easier to make, less expensive. Allows for a degree of automation in circuits i.e. thermostats, float switched, humidistats, timers, etc.

The basic components required by the NEC for motor control circuits are: Disconnect means to physically open the supply conductor(s) going to the motor circuit Controller to start and stop the motor Overload protection to prevent overheating that may result from motor loads that exceed the rated ampacity of the motor

How the circuit works The motor control (definite purpose contactor or relay in this application) employs the use of an electrically generated magnetic field to make or break contact between the supply conductors attached to the relay terminals L1 and L2 and the load conductors attached to relay terminals T1 and T2 that supply the load.

Basic Components and Operation Definite Purpose Contactor (Relay) - Source conductors from the over current protection device attach to L1 and L2 at the top of the relay. The load conductors attach to T1 & T2 at the bottom of the relay and send power to the motor load. A conductor tapped from one terminal on either L1 or L2 (Conductor #1 in diagram) will carry 120 volts to the bottom terminal of the normally closed STOP button on the push button station. L1 (Line 1) Supply Terminals L2 (Line 2) T1 (terminal 1) Load Terminals T2 (terminal 2)

Coil (the coil is inside the definite purpose contactor)– Copper windings in the relay surround an iron core that will create a magnetic field when current is supplied to the coil by pushing the START button. When electric current is applied the magnetic field generated by the coil will close the relay contacts. The relay is rated at 120 V therefore it must have a grounded conductor attached to one terminal of the coil to complete the circuit. An ungrounded conductor (#2) from the top terminal of the START button will attach to the other terminal of the coil. Coil Terminals

Push button station – normally closed (N. C Push button station – normally closed (N.C.) contacts on the stop button (cover portion), normally open (N.O.) contacts on the start button (cover portion). An ungrounded jumper in the base creates continuity between the top terminal of the normally closed stop and the bottom terminal of the normally open start. The START button is a momentary contactor, it does not maintain contact when released. Sends current to the coil (START Terminals) Normally Open Ungrounded Jumper Receives current from relay (STOP terminals) Normally Closed

Auxiliary contactor - mounts to the side of the relay and maintains contact between L1, L2 & T1, T2 conductors by-passing the start button and maintaining the circuit when the START button is released. It is held in place by a lever on the relay contacts. Auxiliary connects to the side of the relay here

How the START button and Auxiliary contactor works When the START button is pressed, current travels to the 120 V coil and a magnetic field is generated. The magnetic field closes the relay contacts which in turn close the auxiliary contact. When the START button is released, the magnetic field is maintained by current travelling through the auxiliary contact. Stop Start Coil C N Auxiliary Contact L 1

One end of a conductor (#3 in the diagram) will be attached to the bottom terminal of the normally open START button. The other end of the conductor will attach to either end of the auxiliary contactor. The bottom terminal of the START button has continuity with the top terminal of the STOP button by means of the ungrounded jumper connecting the two terminals (in the push button station base). The STOP button is normally closed, so current will travel from the START terminal to the auxiliary after the START button is released and it returns to its normally open position. # 1 # 2 #3 COIL L1 L2 T1 T2 Relay START Terminals Ungrounded jumper Current from the bottom START terminal to the auxiliary STOP Terminals

A conductor (red jumper in the relay enclosure) from the other terminal of the auxiliary will connect to the ungrounded terminal of the coil. When the START button is pressed, current travels from the top START terminal to the coil generating a magnetic field that closes the relay contacts. A lever attached to the contacts in the relay mechanically closes the auxiliary contacts and current by-passes the start button through the red jumper once the START button is released. Current travels through the auxiliary to the coil in order to maintain the magnetic field and keep the relay contacts closed and the motor circuit energized. COIL L1 L2 T1 T2 Relay Jumper from auxiliary to the coil

Conductor #1 Ungrounded conductor from L1 to N.C. STOP Conductor # 2 COIL L1 L2 T1 T2 Source Conductors Load Conductors Relay # 3 Grounded Conductor Conductor #1 Ungrounded conductor from L1 to N.C. STOP Conductor # 2 Ungrounded conductor from the top terminal of N.O. START to the coil #2 # 1 Red Jumper from the auxiliary to the ungrounded coil terminal. Bypasses the N.O. START Conductor # 3 Ungrounded from the bottom terminal of N.C. START to the auxiliary

Normally Closed STOP terminals Coil Wiring Diagram N Source Conductors Conductor #1 120 Volts Grounded Conductor (Neutral) Jumper Conductor #2 Jumper L1 L2 Relay Contacts Normally Closed STOP terminals Coil T1 T2 Normally Open START terminals Conductor # 3 Load Conductors Auxiliary Contact M Motor

L1 L2 T1 T2 N M Wiring Diagram Current flow from L1 to the coil when the START push button is pressed and the coil is energized. Contacts closed by the magnetic field generated by the energized coil. Trace the flow of current from L1 to the coil with the START button closed to see how current flows to energize the coil and close the relay contacts. Motor is ON

L1 L2 T1 T2 N M Wiring Diagram Contacts maintained by the auxiliary contact which supplies current to the coil. Current flow to the coil when the START button is released. Trace the flow of current from L1 to the coil with the START button open to see how current flows to maintain the relay contacts. Motor is ON

L1 L2 T1 T2 Wiring Diagram N Motor is OFF M When the normally closed STOP button is pushed it opens, the circuit is broken and the magnetic field collapses. A spring on the relay contacts and in the auxiliary contact opens the contacts and the circuit is de-energized. Motor is OFF